diff --git a/common.sh b/common.sh
new file mode 100755
index 0000000..ed44bba
--- /dev/null
+++ b/common.sh
@@ -0,0 +1,62 @@
+#!/bin/bash
+
+## debug
+# set -x
+
+. ~/.noaa.conf
+
+declare -A levels=([DEBUG]=0 [INFO]=1 [WARN]=2 [ERROR]=3)
+log_level=${LOG_LEVEL}
+
+## log function
+log() {
+    local log_message=$1
+    local log_priority=$2
+
+    #check if level exists
+    [[ ${levels[$log_priority]} ]] || return 1
+
+    #check if level is enough
+    (( ${levels[$log_priority]} < ${levels[$log_level]} )) && return 2
+
+    #log here
+    echo "${log_priority} : ${log_message}"
+}
+
+## current date and folder structure
+START_DATE=$(date '+%d-%m-%Y %H:%M')
+FOLDER_DATE="$(date +%Y)/$(date +%m)/$(date +%d)"
+
+## sane checks
+if [ ! -d "${NOAA_HOME}" ]; then
+	mkdir -p "${NOAA_HOME}"
+fi
+
+if [ ! -d "${NOAA_OUTPUT}" ]; then
+	mkdir -p "${NOAA_OUTPUT}"
+fi
+
+
+if [ ! -d "${METEOR_OUTPUT}" ]; then
+	mkdir -p "${METEOR_OUTPUT}"
+fi
+
+if [ ! -d "${NOAA_AUDIO}/audio/" ]; then
+	mkdir -p "${NOAA_AUDIO}/audio/"
+fi
+
+if [ ! -d "${NOAA_OUTPUT}/image/" ]; then
+	mkdir -p "${NOAA_OUTPUT}/image/"
+fi
+
+if [ ! -d "${NOAA_HOME}/map/" ]; then
+	mkdir -p "${NOAA_HOME}/map/"
+fi
+
+if [ ! -d "${NOAA_HOME}/predict/" ]; then
+	mkdir -p "${NOAA_HOME}/predict/"
+fi
+
+if [ ! -d "${NOAA_OUTPUT}/image/${FOLDER_DATE}" ]; then
+        mkdir -p "${NOAA_OUTPUT}/image/${FOLDER_DATE}"
+fi